"I've been riding since 1999, and it was far more reliable and less crowded before," Skiles said. "If they could get to where it is running regularly, I'd go back . . . but I can't afford to be three or four hours late to work."

VRE riders have become frustrated with the service in recent months as trains seem to encounter more frequent problems and are crowded with people standing in narrow aisles and on winding staircases.

Between July 12, when a new operator, Keolis Rail Services America, began running VRE's trains, and Nov. 30, there were about 488 delays and 10 cancellations. Forty-six of those delays were an hour or more long. In the same period the year before, there were four cancellations and 300 delays, with only eight an hour or longer, according to a Washington Post analysis of VRE service-disruption reports. (VRE did add one new morning express train this summer).

"It's irrelevant why engines are failing," said Gregg Baxter, general manager for Keolis's local operation. "We know we have an obligation to get them fixed and stop the problem."

Despite a few massive delays, VRE's overall on-time performance remains fair, VRE officials said. It has recovered from a tumble it took this summer when it slipped as low as 63 percent. In October it was 88.9 percent, up from 87 percent a year earlier. In November, that figure was 85.8 percent, up from 82 percent, according to VRE data. A train is counted as "on time" if it is less than five minutes late.

"In the corridors we run - Interstate 95 and Interstate 66 - I don't believe on a regular basis you can get into your car, drive to work and be within a five-minute window nine out of 10 times," VRE spokesman Mark Roeber said.

In The Post's analysis, the most frequent causes of delays since July 12 have been speed restrictions; mechanical problems; switch and signal malfunctions; calls for emergency passenger assistance; and delays due to many passengers boarding.

In some ways, the system is a victim of its own success.

When VRE was created in 1992, its mission statement was to serve 10,000 riders daily. In November, the average daily ridership was 17,700, up from roughly 16,600 the year before, Roeber said. The system, with a capacity of roughly 20,000, hit its highest ridership day ever last month, with 19,540 riders on Nov. 9.